The Central Bureau for Astronomical Telegrams: A Case Study in Astronomical Internationalism

Astronomical news travels fast. Within hours, first details of a comet or nova get to astronomers all around the world. Of course, all sorts of news travels fast these days, which is often cited as a wonder of modern technology. It may be a surprise to learn, therefore, that long before the global media culture arose, before television, and even before radio, astronomers set up their own system to spread scientific alerts. Astronomers recognized that national hostilities inhibited their research, and so, long before the United Nations or the League of Nations, astronomers designed procedures to evade such hostilities.

For more than a century, when the internationalist needs of astronomical communications have collided with nationalist politics, astronomy has consistently won far out of proportion to its political strength. Astronomy's successful internationalism is epitomized by the Central Bureau of Astronomical Telegrams, founded in 1882. When the International Astronomical Union was founded in 1919, its Commission 6 assumed responsibility for the Bureau. The Bureau has overcome every administrative, economic, and military obstruction the world has thrown at it. It even kept functioning without interruption through World Wars I and II, disseminating news of transient phenomena to all subscribers regardless of nationality.

How Cosmic Events Impose Internationalism on Astronomers

Several important categories of celestial phenomena occur unpredictably in time and in sky location. Comet and asteroid discoveries, nova outbursts, supernova explosions, and unexpected behavior or previously-known objects (such as sudden storms on Mars or Jupiter) are all phenomena which astronomers feel urgency in studying. Astronomers must observe them quickly, with virtually any available instrument.

"Among such discoveries are those of planets and comets, or of bodies which are generally so faint as not to be seen, except through the telescope, and which being in motion, their place in the heavens must be made known to the distant observer, before they so far change their position as not to be readily found. For this purpose the ordinary mail conveyance, requiring at least ten days, is too slow, since in that time the body will have so far changed its position as not to be found, except with great difficulty; and this change will become the greater if the body is a very faint one, for in that case it could only be discovered on a night free from moonlight, which of necessity in ten or twelve days must be followed by nights on which the sky is illuminated by the Moon, and all attempts to discover the object would have to be postponed until the recurrence of a dark night. Indeed, even then the search often proves in vain; and it is not, in some cases, until after a set of approximate elements are calculated and transmitted, that the astronomers on the two sides of the Atlantic are able fully to cooperate with each other." (Joseph Henry, quoted in Monthly Notices of the Royal Astronomical Society, 1874, p. 185)

The explanation continues:

"Although the discovery of [minor] planets and comets will probably be the principal subject of the cable telegrams, yet it is not intended to restrict the transmission of intelligence solely to that class of observation. Any remarkable solar phenomenon presenting itself suddenly in Europe, observations of which may be practicable in America several hours after the Sun has set to the European observer; the sudden outburst of some variable star similar to that which appeared in Corona Borealis in 1866; unexpected showers of shooting-stars, &c., would be proper subjects." (Monthly Notices of the Royal Astronomical Society, 1874, pp. 185-186)

Comets and Asteroids

Comets can be found in any part of the sky, at any brightness, and moving at any rate in any direction. When a comet is discovered, the discoverer immediately tells the Central Bureau for Astronomical Telegrams its position, brightness, and (if determined) its apparent direction and rate of motion. Comets are frequently found under conditions in which the discoverer cannot track them long enough to establish their rate and direction of motion against the background of fixed stars - they may be near the horizon and setting, they may be found just before dawn glares them out, they may be spotted in a sky that quickly clouded over, or personal circumstances may preclude further observing. Comets must be recovered before they move too far from the discovery position, so that their orbits can be determined, and from those orbits, the ephemerides for future sightings. Given two days from first sighting, a comet can move several degrees away from the first position, and fade by two magnitudes. The differences in position and brightness grow so great that a discovery unobserved for three or four days is in grave danger of becoming utterly lost. It is extremely important that astronomers elsewhere be alerted so they can find the unexpected interloper and pin down its positional and visual characteristics. So the Central Bureau immediately cables professional observatories and reliable amateur observers west of the first reporting station, in longitudes where it is still nighttime, hoping that at least one will at that moment have clear skies and staff and equipment they can shunt to hunt the comet. As the hours tick by, observatories farther and farther west around the Earth join the hunt, until sufficient observations are confirmed to make the comet unlikely to be lost. Usually, by the time the comet is next observable from the discovery location, confirming observations are in hand, and the first reporting observer learns whose names will be attached to that interplanetary iceberg. It is invariable in the discoverer's interest to alert the whole world absolutely as soon as possible.

There are also minor planets (asteroids) swarming around the inner solar system by the thousands. A few of these orbit strikingly close to Earth. At such approaches, they brighten dramatically, making a rock barely a kilometer across visible to amateur telescopes. Simultaneously, they sprint across the sky, making it hard to take a time-exposure (they move too fast) and hard to make an accurate positional fix (requiring a trained team with cross-hairs and setting circles), just when it is most important. Such asteroids can actually collide with our planet, with results presently popularized regarding the Cretaceous/Tertiary extinction.

Stellar Outbursts

Eruptive variable stars ― novae and supernovae ― are very important, fast-changing stages late in stellar evolution. Unfortunately, they occur so unpredictably that observations of the brief, insufficiently-understood brightening phase(s?) are very rare. Therefore, it is important to obtain both brightness measurements and spectra of all such outbursts absolutely as early as feasible.

Novae and supernovae do not move against the background of stars, and so a single positional fix suffices to locate them. Their brightness and spectral behavior, however, change radically, and as rapidly as anyone has yet measured ― brightness flickerings of tenths-of-seconds are known for at least a few novae. Therefore, brightness requires continual monitoring. The spectrum also changes enormously as assorted layers of the erupting star lunge through wildly different temperatures, pressures, and densities. This gives some of our best information about the insides of stars, and so it is again critically important to obtain spectra very frequently, especially when the eruption is fresh.

Again, observatories around the globe must be alerted because longitude and weather patterns will only allow observations at some of them, and other circumstances of equipment and personnel further reduce the number at which the critical observations can be made. (For example, sensing hardware at the tail-end of the telescope, such as a photometer or a spectrograph, is fitted to a major telescope in a many-hours-long daylight operation, and usually remains attached for an observing run lasting several consecutive nights. If the telescopes at a well-located, well-equipped, well-staffed, and cooperative observatory are outfitted for other research and incapable of the type of measurements needed for the fresh nova, that observatory can make no contribution, however eager it might be to help.) So again, the alert must go out as rapidly and broadly as technology and funding permit.

All astronomers know these factors. They are inherent in the astronomical objects being studied and utterly independent of astronomers of planet Earth. It is up to astronomers to accommodate their research methods to their objects of study.

Premature concepts in International Information Flow

Communications technology, not politics, has been the limiting factor in dissemination of astronomical news. Though it has always been obvious to astronomers that instant bulletins would be of great value, they have also appreciated the impossibility of achieving that till quite recently. In Tycho's era, centuries before the Universal Postal Union regularized international mail, a central location would have served best.

"Tycho Brahe ... keenly felt the importance of closer intercourse between fellow astronomers .... he tells that before King Frederik II of Denmark offered him the island Hven as site for an observatory he had had plans for settling in Basel, one of the reasons for this choice being that Basel is located so to speak at the point where the three biggest countries in Europe, Italy, France, and Germany meet, so that it would be possible by correspondence to form friendships with distinguished and learned men in different places. In this way it would be possible to make my inventions more widely known so that they might become more generally useful.' Into these remarks may be read a desire for a centre, from which useful astronomical news could be distributed. Such a centre, however, took its time to materialize." (Vinter Hansen, 1955, p. 17)

In the early 1800s, printing and postal improvements began to make a newsletter practical, and Astronomische Nachrichten, the first international astronomical newsletter, was born. Its founder, Heinrich C. Schumacher, an expert celestial mechanic, established it in 1823 at his observatory in Altona, Holstein, then the second-largest city in Denmark (Beekman, 1983, pp. 488-489). Altona was immediately northwest of Hamburg, Hanover, across the Danish boundary set in 1815 at the Congress of Vienna. (Altona is now well within Hamburg city limits.) During the Prusso-Danish War of 1848,

"the existence of his observatory at Altona was in doubt. The astronomers throughout the world rallied for the protection of Schumacher, and almost every civilised country made through its representatives urgent appeals to the Danish Court that the observatory and its respected director should be spared and protected. Lord Palmerston, pressed to action by the Council of [the Royal Astronomical] Society, obtained assurances from the Danish Government that neither the Professor nor his establishment should be affected." (Stratton, 1934, p. 363)

Schleswig and Holstein were incorporated into what became Germany, and upon Schumacher's death in 1850, Astronomische Nachrichten was transferred to C. N. Adalbert Kruger, celestial mechanic at the Kiel Observatory, on the north edge of Holstein.

Telegraphy was improving markedly during this period. The first astronomical telegram center was established by the Imperial Academy of Sciences in Vienna in 1869, limited to comet discoveries but with a gold medal for incentive. (Gingerich, 1968, p. 37; Vinter Hansen, 1955, p. 18)

The Atlantic Cable

The need for a broader service was apparent to "some of the principal astronomers in Europe and America," however, and so C. H. F. Peters, the prominent director of Hamilton College Observatory in Clinton, New York, laid the need before the Committee of the Smithsonian Institution. They "immediately applied to the Directors of the Associated [Trans-Atlantic Cable] Companies, who at once granted the free use of all their lines for the object in question, both from Europe and America, for a limited number of telegrams during each year." (Monthly Notices of the Royal Astronomical Society, 1874, p. 185)

"A very important concession has been made to the Smithsonian Institution by the Directors of the Associated Trans-Atlantic Cable Companies, who have agreed to transmit gratuitously between Europe and the United States, a limited number of short messages on astronomical subjects. Under this arrangements two telegrams have already been received from the United States by the Astronomer Royal, who on his part has undertaken, at the request of Dr. Henry, Secretary of the Smithsonian Institution, to forward from Europe any message announcing an important astronomical discovery. The Directors of the Associated Companies have consented that ten messages, of ten words each, may be sent free over the cables annually. This liberal concession on the part of the Directors cannot be too highly appreciated by astronomers generally, and especially by the fellows of this Society.

"In conformity with this agreement the Astronomer Royal will be prepared to forward any important astronomical message, limited to ten words, which may be sent to him for this purpose from the principal European astronomers. Royal Observatory, Greenwich, April 8, 1873." (Airy, 1873)

The matter was further elaborated on 10 months later:

"The great value of this concession on the part of the Atlantic Telegraph and other companies cannot be too highly prized, and our science must certainly be the gainer by this disinterested act of liberality. Already [minor] planets discovered in America have been observed in Europe on the evening following the receipt of the telegram, or within two or three days of their discovery. The Council are glad to be able to announce that the Director of the Imperial Russian Telegraph has also given permission for the free transmission of messages relating to new astronomical discoveries within the boundaries of the Russian Empire." (Monthly Notices of the Royal Astronomical Society, 1874, p. 186)

The Central Bureau for Astronomical Telegrams

While this was a major advance, things were not quite perfect. There were technical difficulties with transmission errors, particularly in numbers for coordinates (causing observers to look in the wrong place), and "national vanities had showed up." (Vinter Hansen, 1955, p. 18, referring to Wilhelm Forster, 1879, p. 345)

So Forster proposed establishing a central news bureau, whose creation was spurred by general agreement that bulletins on the great September comet of 1882 were "thoroughly inadequate." (Vinter Hansen, 1955, pp. 18-19; Forster 1881, Forster 1882, and Kruger 1883) Forster nominated a committee of eight to set up the Centralstelle in 1882 in Kiel with Kruger as director. (Stratton, 1934, p. 363) The director would decide which items required expensive telegrams and which could be relegated to the established ― and far more economical ― columns of Astronomische Nachrichten. By this time the journal was no longer the personal property of its editor; in 1881 a share of control was assumed by the Astronomische Gesellschaft, which had been founded at Heidelberg in 1863.

"Though primarily German, this body has always been alive to the value of international co-operation in astronomy. Its statutes specifically stated that its membership was not bounded by nationality, and the list of those attending its first meeting includes members present from ten countries." (Stratton, 1934, p. 363)

From the 1880s to the beginning of World War I, the Centralstelle operated smoothly at Kiel, under Kruger and his successor, H. Kobold.

But by no means was it astronomy's only international cooperative venture. In 1887, Observatoire de Paris hosted the International Astrophotographic Congress at which the monumental Carte du Ciel project was begun (Winterhalter, 1889). The project required meetings every few years to monitor progress, and gradually these meetings (usually in Paris) came to include extra sessions on astronomical topics unrelated to the Carte du Ciel itself. Other international astronomical meetings were also held, for example at the opening of Yerkes Observatory in Williams Bay, Wisconsin, in 1898, and at the St. Louis World Fair in 1904.

The guns of August, 1914, however, severed telegraphic and postal links between the belligerents. It became impossible to communicate directly between, say, the Royal Greenwich or Paris observatories and Kiel.

Prof. Kobold therefore ceded the Central Bureau for Astronomical Telegrams on 3 November 1914 to another celestial mechanic, Prof. Elis Stromgren, director of Copenhagen Observatory, in adjacent but neutral Denmark, for the duration of the hostilities. Kobold and Stromgren knew each other well ― Stromgren had earlier been an assistant at Kiel and knew how the Central Bureau worked. (Vinter Hansen, 1955, pp. 19-20) In the early months of World War I most people thought the war would be brief, but it dragged on almost until the end of 1918.

"It was possible for [Stromgren] all through the war to keep up astronomical intercourse and satisfactory news service between astronomers all over the world." (Vinter Hansen, 1955, p. 20)

Losing the Peace

The problems with national antipathies were thus overcome during World War I. However, it proved very difficult to keep a lid on after the Armistice was signed. During the war, astronomers could travel little and many were occupied with war-related problems. When peace finally came, astronomers could once more travel, but residual jingoism and bitterness prevented many in the Allied countries from wanting anything to do with anyone in the Central Powers. Thus, in 1919 when the International Astronomical Union was formed as part of the International Research Council, only entente powers were invited to adhere at first, followed shortly by neutral countries.

"Now each of the pre-war organizations for international cooperation was concerned with its own particular branch of astronomy; for they had come into being one at a time, as the necessity for them had been felt. It was clear, however, that it would be much more convenient for every one concerned if they could be brought together into a single body. And so, when these various organizations died a natural [sic] death as a result of the war, it was decided to revive them, not in their original form, but as branches of an all-embracing International Astronomical Union. This was accomplished at a meeting in Brussels in 1919 of the leading scientists of the allied countries; and in 1922 the first meeting of the International Astronomical Union was held in Rome .... At first the I.A.U. consisted of thirty-two separate 'commissions,' fourteen of which could be regarded as the direct descendents of pre-war organizations." (Waterfield, 1938)

Losing countries were not welcome to adhere for many years ― though "Astronomers from countries not adhering can attend meetings as visitors and take part in the discussions without voting." (Waterfield, 1938)

The national antipathies resulted in some astronomers refusing to deal with Copenhagen, feeling it too closely connected with Kiel, which was German and therefore tarred with atrocities. The popular director of Observatoire de Paris, Benjamin Baillaud, served briefly as intermediary between such people and Copenhagen. Then the brand-new International Astronomical Union, under provisional leadership, set up its own Central Bureau for Astronomical Telegrams ― neither at Kiel nor Copenhagen, but seeking a more neutral location (Gingerich, 1968, p. 38), at Uccle, the Belgian royal observatory in Brussels, under Prof. G. Lecointe, starting 1 January 1920. Copenhagen served as intermediary between the new Uccle and the old Kiel bureaus until the IAU held its first full meeting, in 1922. The IAU thereupon transferred its Central Bureau from Uccle back to Copenhagen as of October, 1922. From then until his death, Elis Stromgren directed the IAU Central Bureau for Astronomical Telegrams from Copenhagen Observatory and maintained friendly relations with Kiel. (Hoffleit, 1947, p.6)

World War II

Denmark was unable to keep out of World War II. Germany invaded in April, 1940, and occupied Denmark for the rest of the war. Elis Stromgren succeeded in keeping the Bureau communicating world-wide, however. "He even obtained permit to send code telegrams, via the Lund Observatory, [in neutral] Sweden, to subscribers in allied countries, and the IAU circulars, although often late in arriving, generally did reach their wide-spread destinations." (Vinter Hansen, 1955, p. 20) The routes were often circuitous: IAU Circular 901, for example, arrived at Harvard Observatory in 1942 bearing an Brazilian stamp (Overbye, 1980, p. 93); it doesn't say how the data got from Sweden to Brazil. In the few times when Stromgren could not even get messages out through Sweden, he made connections through Zurich, Switzerland, also a neutral for relaying telegrams worldwide. Connections could always be made either through Sweden or Switzerland. (IAU Transactions, Vol. VII, p. 86)

There was, however, a distinct decline in traffic in 1943-44, at the worst period of the German occupation of Denmark. (IAU Transactions, Vol. VII, p. 87) The decline probably reflects the diversion of skywatchers into the war effort, thereby reducing the number of sky events noticed, as well as the difficulty of telling Copenhagen about them.

After World War II, communications links became less troublesome, and more astronomers again looked skyward and reported discoveries. The effort the Central Bureau once spent routing messages was now devoted to processing the increased data.

Elis Stromgren died in 1947 and was succeeded by his assistant, Julie Vinter Hansen. She had assisted at Copenhagen for many years, though she spent World War II at Lick Observatory in California. She returned to Denmark when the war ended and resumed her assistantship under Stromgren, succeeding to his work upon his death. (Ashbrook, 1960, p. 328) She remained director until her own death, in 1960. By 1964, the ongoing duties of the Bureau were overwhelming her assistant and successor, K. A. Thernoe, and so Fred Whipple offered to transfer the Bureau to the Smithsonian Astrophysical Observatory, which cohabits with Harvard Observatory in Cambridge, Massachusetts; Whipple was director of both Smithsonian and Harvard observatories. Owen Gingerich directed the Bureau when it moved to Massachusetts.

The Central Bureau at the Hub of the Universe

"Thanks to B. G. Marsden, Director of the Bureau, and to the continued support of the Smithsonian Astrophysical Observatory, astronomers have at their disposal an efficient and relatively inexpensive mechanism for prompt cooperation that must be the envy of scientists working in other fields." )P. Simon, President of Commission 6, in IAU Transactions, Vol. XVI A1, 1976, p. 195)

As early as 1883, Harvard College Observatory served as North American telegram relay center ― receiving all telegrams from the Centralstelle and relaying them to American subscribers. Several similar branch offices around the world have sprung up and died off sporadically over the last century, but Harvard has the longest and steadiest record. Beginning in 1926, the "Harvard Announcement Cards" constituted this continent's equivalent of the IAU Circulars. (Gingerich, 1968, pp. 37-38) During Harlow Shapley's reign as Observatory Director, they were all signed "Harlow Shapley," but while he oversaw most of the operation, many of the orbital elements and ephemerides they contained were actually composed by others ― by Leland Cunningham during his assistantship there, 1935-42. The Shapley signature proved very useful toward acquiring donations; Shapley was able to point to important work done despite a pathetically small endowment. (Cunningham, 1985)

The bulk of the labor consisted of the tedium of decoding Copenhagen telegrams, re-coding them for American distribution since until World War II Copenhagen and Harvard used different telegraphic codes, and conveying them to the telegraph office. Initially the Harvard cards were simple relays of Copenhagen data, but they grew to include other ephemera of American interest, as well as data on their way to Copenhagen. (Cunningham, 1985) When the Bureau was transferred, the Harvard Announcement cards terminated with card 1676, and were succeeded by IAU Circular 1884; Circular numbers reached 5152 by the end of 1990.

The main part of the operation is carried on today in the office of Brian Marsden with active VAX and IBM computer terminals as well as Telex and assorted other electronic links through the Smithsonian's telecommunications center until 1978, and managing its own since then. Subscribers with personal computers could access the very latest listings by modem[, and since the mid-1990s, on the World Wide Web]. Marsden has an assistant, Daniel Green, and immediate access to the entire Center for Astrophysics staff and library ― one of the largest concentrations of astronomical expertise on this planet. Routine celestial mechanics still makes up the bulk of the work, with special attention to keeping new-found objects from getting lost.

The main consideration is to pin down the ephemeral events in the heavens, but where earthly circumstances allow options, lesser criteria do enter. The judgement of a thinking, feeling, experienced human is vital when an incoming message has to be interpreted. How likely is the source to be mistaken, or trying to pull a fast one for quick glory? Which observatories should be dunned for confirmatory monitoring ― who are the assigned observers this evening, who sounded eager last time, who felt it a burden, who could use a little favorable notice, who should get no more than necessary?

Commission 6

Commission 6 is largely concerned with the administrivia of keeping the Central Bureau operating. It decides on formats, amendments to the standard transmission code, subscription billing intervals, and the like. Commission business meetings at Congresses are brief, cut and dried. Reports of the Director and President are distributed in advance, consensus always reigns on major issues, and discussion achieves consensus on minor ones. Membership has largely been intended to represent the message relay centers, wherever in the world they may be, plus a few comet and orbit experts. The vast bulk of the work is done not by the commission but by the Central Bureau. (Cunningham, 1985)

Even within the IAU, Commission 6 has striven for the broadest possible base:

"[Marsden] noted that all Commission members present at the Meeting were, without exception, also members of Commission 20 [Positions and Motions of Comets, Minor Planets, and Satellites], which might give the impression that Commission 6 was mainly a sub-section of Commission 20. This was by no means the case, and to stress this fact a special effort had been made some years previously to include representatives from other Commissions. However, these had taken little or no part in Commission 6 activities. The reason might be that rapid dissemination of astronomical data still remained, as in the past, mainly of interest to observers of minor planets, comets and related objects, while it was evident that workers in other fields were entirely satisfied with the operation of the Bureau." (IAU Transactions. Vol. XVIII B, 1982, p. 79)

Tokens of Appreciation

The Bureau's funding has varied markedly over the years. Typically the host institution underwrites either staff salaries or overhead, sometimes both. In Copenhagen, until October, 1929, an unnamed "outside source" provided financial assistance. (IAU Transactions, Vol. III, 1928, p. 276) Since 1929, the IAU has paid yearly subsidies toward the Bureau's work, but these have grown far slower than expenses. While in Copenhagen, very liberal donations were made by the Danish Rask-Orsted Foundations. Additional donations come from other Danish foundations. These were both contributions toward operating expenses and advances against subscription income uncollected due to World War II, when most recipients of telegrams were prevented from paying for the service. (IAU Transactions, Vol. VII, 1948, p. 276) Those loans were eventually paid back, though the last of them lingered years after the guns fell silent. The foundations' motives probably reflected local pride about being the world center of something.

Since the 1950s, subscriptions of various categories have covered the vast majority of the Bureau's operating funds. Originally these only paid for outgoing messages, but they have been increased deliberately since the 1965 move to Harvard to cover as much of the infrastructure (computing time, processing incoming messages, and part of the staff salaries and building overhead). From the time of the move, the Smithsonian Astrophysical Observatory paid for the director's salary, while 1965 and 1966 subscriptions totaled $7,328 – and the IAU subsidy was $666/year. This "pays for very little of the actual operation of the Bureau, but it provides considerable moral support and gives the operation a desirable flexibility that it would not otherwise have." (Gingerich in IAU Transactions, Vol. XII A, 1967, p. lxxxii) Certain low-priority types of message now also trigger a line-charge, analogous to the page-charges of professional journals, generating further income. IAU's cash contribution, though increased to 10,000 Swiss francs per triennium, is now less than 5 percent of the Bureau's actual running costs. It remains, however, "tangible proof of the high regard in which the Bureau is held by the Executive Committee, and a letter to this effect received from the General Secretary was noted with appreciation." (Commission President Jan Mers in IAU Transactions, Vol. XVIII B, 1982, p. 79) It is "used partly to ensure that Circulars are supplied to important observatories in regions of the world whence it is difficult or impossible for us to receive payment." (Marsden in IAU Transactions, Vol. XV A, 1973, p. 17)

Conclusions: Strident Internationalism Victorious

The Central Bureau for Astronomical Telegrams has achieved its goals for more than a century. It receives information from all around this planet about transient events all around the universe. It disseminates the data to all observers it can identify as needing such service. The Bureau's administration has changed only once, from an independent commission to an International Astronomical Union commission. At that same time, more than a dozen other international astronomical programs became IAU commissions; almost half of the new IAU's commissions traced their heritages to previous arrangements. The Bureau moved from Kiel to Copenhagen, briefly to Brussels, and eventually to Cambridge, Massachusetts, always to take advantage of the best site to and from which to relay messages, consistent with the availability of a first-class celestial mechanic. Citizens of many countries participate in Commission 6. The Bureau's avowed purpose has authorized methods of data transmission that evade obstructions imposed by wars and any other causes. It has succeeded in this at all times, employing relays at observatories wherever they may be handy. Thus the Central Bureau for Astronomical Telegrams demonstrates astronomy's long-term, ongoing, strident internationalism.

Winterhalter, Albert G. The International Astrophotographic Congress and a Visit to Certain European Observatories and Other Institutions: Report to the Superintendent. Appendix I to the Washington Observations for 1885. Government Printing Office, Washington, D.C., 1889, pp. 38, 42-46, 68-71.